Ink ribbon cartridges for printers are well known and rely on a substantially longitudinal advance of the ribbon in the course of a printing operation. Such longitudinal advance is uneconomical taking into account the unutilized area of the ribbon in the printing operation.
Accordingly, efforts have been made to maximize the area of the ribbon utilized in the printing operation. These include a feed of the ribbon such that the characters are over-struck thereon. Conventionally, the ribbon is shifted approximately 1/5 of the width of a conventional character to achieve a so called 4/5 over-strike. This is generally acceptable on the finished product for all characters except those in which there are a succession of horizontal lines such as for the letters E and F and for underlining. Under such circumstances, the horizontal stroke produced on the paper is formed at its left end on a part of the ribbon which is struck five times, whereas, at the right end, it is formed on a part of the ribbon struck once. As a consequence, the resulting stroke is uneven in appearance.
In order to avoid this, it is known to vertically displace or dither the ribbon so that the horizontal strokes will be displaced on the ribbon to avoid striking the same region of the ribbon.
This is conventionally achieved by means external of the cartridge and generally, by displacing the entire cartridge and the ribbon therewith. Such conventional construction is complex, costly and generally requires a power drive.